Labeling with thermally conductive pads

ABSTRACT

A method of labeling an object includes selectively applying focused energy to thermally conductive pads on the object to create a label on the object. The conductive pads are disposed adjacent to a thermochromic layer.

BACKGROUND

Optical discs have fast become an industry standard for data storage inthe fields of computers, video, and music. Optical discs include, butare not limited to, compact discs (CDs), Digital Video (or Versatile)Discs (DVDs) and game system discs in a variety of formats. Commerciallyproduced optical discs usually have digital data recorded on one side ofthe disc and a visual display printed on the other side of the disc.

In some instances, optical discs are created that can store data on bothsides of the disc. However, in many cases, it is desirable to limit theoptical disc data to a single side of the disc, leaving the other sideof the disc for printed text, patterns or graphics. The printed labelingon a non-data side of an optical disc can include a decorative design,text identifying the data stored on the disc, or both.

As optical technology has advanced, writeable and rewritable opticaldiscs and equipment for writing onto the discs have become reasonablypriced within the grasp of ordinary consumers. Thus, many consumerscurrently have the ability to store data on an optical disc with homeoffice equipment.

However, very specialized and expensive equipment is required to printlabeling on an optical disc. Consequently, the labeling of discs by mostconsumers is typically limited to printing on separate adhesive labelsthat are adhered to the non-data side of the disc or hand-writing with amarker directly on the disc or an adhesive label.

SUMMARY

A method of labeling an object includes selectively applying focusedenergy to thermally conductive pads on the object to create a label onthe object. The conductive pads are disposed adjacent to a thermochromiclayer.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate various embodiments of the presentinvention and are a part of the specification. The illustratedembodiments are merely examples of the present invention and do notlimit the scope of the invention.

FIG. 1 is an exploded view of an optical disc and detailed insetaccording to one embodiment of the present invention.

FIG. 2 is an exploded view of another optical disc and detailed insetaccording to one embodiment of the present invention.

FIG. 3 is an exploded view of another optical disc and detailed insetaccording to one embodiment of the present invention.

FIG. 4A is a side view of a first layer of an optical disc according toone embodiment of the present invention.

FIG. 4B is a side view of first and second layers of an optical discaccording to one embodiment of the present invention.

FIG. 4C is a side view of first, second, and third layers of an opticaldisc according to one embodiment of the present invention.

FIG. 4D is a side view of first, second, third, and fourth layers of anoptical disc according to one embodiment of the present invention.

FIG. 5 is a diagrammatical side view of an optical disc labeling systemaccording to one embodiment of the present invention.

FIG. 6 is a top view of an optical disc with a label made according toone embodiment of the present invention.

Throughout the drawings, identical reference numbers designate similar,but not necessarily identical, elements.

DETAILED DESCRIPTION

Writeable and rewritable optical disks include materials that changeoptical properties (e.g. reflection, refraction, absorption,transmission, diffraction, and scatter) when heated by a focused energysource (e.g. a writing laser). By selectively changing the opticalproperties of particular points along an optical disc's spiral datatrack and leaving other areas unaffected, digital data is recorded onthe disk that computers and/or audiovisual equipment can read. Somechanges in optical properties, for example, a change in reflectivity,are also readily visible to consumers and typically indicate that datais stored on the optical disc. Therefore, in addition to storing data onan optical disc, it is also possible to create visible printed patternsor graphical designs on the disc by selectively changing the opticalproperties of portions of the disc.

However, lasers used to write data onto the optical disk data track arevery tightly focused and of very high resolution (˜12,000 dpi) tofacilitate storage of very large amounts of data. Such high resolutionlasers require thousands of laser strikes to create one 300 dpi visiblespot. Consequently, it would take a very long time, perhaps an hour ormore, to write a small printed pattern or graphical design onto aconventional optical disc in this manner. As a result, it is not commoncurrently for printed patterns and/or graphical designs to be writtenonto conventional optical discs using the same laser that also writesdigital data to the disc.

The present specification describes a mass media storage device, such asan optical disc, and methods of making and using such an optical disc.The specification also describes methods of labeling mass media storagesdevices or any other object by the application of focused energy.

As used in this specification and the appended claims, the term “opticaldisc” is used broadly to encompass discs for recording music, pictures,video and/or software, etc.. An optical disc includes, but is notlimited to, writable and rewritable storage devices including, but notlimited to, Compact Discs (CDs), Compact Disc Read-Only Memory (CD-ROMs)and Digital Video (or Versatile) Discs in various formats.

“Label” or “labeling” means any text, printed pattern, graphical designor combination thereof on an object. If a label is added to an opticaldisc, typically the label is found on one side of the optical disc,although this is not necessarily the case. “Printed pattern”, means anytext, letters, words, symbols, or characters that are found on an objectas part of a label for that object. “Graphical design” means any graphicor image that is found on an object as part of a label for that object.“Uniform” means having the same or substantially the same design orpattern throughout.

As mentioned above, it is possible to write labels on current opticaldiscs by applying a laser to the discs in certain patterns. Theapplication of the laser changes the optical properties (such asreflectivity) of the exposed portions of the disc, resulting in patternsthat can be made large enough to be visible to users. Lasers for writingdigital, machine-readable data on optical discs are typically focused atabout 2.2 μm. Therefore, if such a laser is used to also write a labelonto a disc, because of the extremely small pixel size that wouldresult, it takes a very long time to produce labels.

While typically, the smaller the pixel size, the better resolution in aprinted product, a 2.2 μm pixel size is unnecessarily small to print aquality label. Therefore, an optical disc is described below forfacilitating faster labeling without compromising data storagecapability. Subsequent to the description of the optical disc itself,methods for making an optical disc are discussed, followed by adiscussion of actually creating a label on the optical disc. However, itwill be understood that the methods described herein are not limited tolabeling optical discs. The methods and apparatus described below may beimplemented with any object to facilitate labeling by the application offocused energy. The particular implementations described below withreference optical discs are therefore exemplary in nature, and notlimiting. For example, the labeling techniques and apparatus describedbelow may be applied to bottles, cans, or any other objects.

Turning now to the figures, and in particular FIG. 1, an exploded viewof an optical disc (100) is shown according to the principles describedherein. The optical disc (100) includes a label side (102) designed tofacilitate labeling thereon by the application of focused energy.Instead of a long spiral track or an unusable surface typical of mostoptical discs, the label side (102) of the optical disc (100) includes aplurality of thermally conductive pads (104) formed on an insulatinglayer (106). The insulating layer (106) may include a polymer or otherinsulating material. The thermally conductive pads (104) formed on theinsulating layer (106) are shown in a detailed inset (108) as they aregenerally not visible to the naked eye. The making of the thermallyconductive pads (104) is discussed in detail below with reference toFIGS. 4A–B.

As shown in FIG. 1, the thermally conductive pads (104) are eachdistinct and may be hexagonal. However, while the hexagonal shapes showncan be densely packed, the shape of the thermally conductive pads (104)is not so limited. Any polygonal shape, and any other shape includingany combination of straight and/or curved lines, may also be used forthe pads (104). For example, the thermally conductive pads (104) may becircular as shown in FIG. 2, or elliptical as shown in FIG. 3.

The size of the thermally conductive pads (104) can be set at anydesired size and will correspond to the size of a pixel in the labelthat is to be produced on the disc (100). For example, the size of thethermally conductive pads may be larger than approximately 5 μm. In someexamples, the size of the conductive pads (104) is between approximately5 and 50 μm. Within that range, in some examples, the size of theconductive pads is about 32 μm.

The thermally conductive pads (104) are arranged adjacent to athermochromic layer (110) that is discussed in more detail below withreference to FIGS. 4C–D. The thermochromic layer (110) includesthermochromic materials that change in optical density when heated.Changes in optical density may be visible to the human eye and expressedin a variety of different colors, depending on the thermochromicmaterial. For example, the thermochromic layer (110) may include leucodye. The thermochromic layer (110) may be covered with an opticallytransparent layer (112) to protect the thermochromic layer (110) fromscratches or other damage. Preferably, the optically transparent layer(112) will not absorb energy of wavelengths associated with laserstypically used to read and/or write optical discs. The opticallytransparent layer (112) may be polycarbonate or another material and isalso discussed below with reference to FIG. 4D.

The pixel size of the thermally conductive pads (104) is substantiallylarger than the typical focus size of an optical writing laser,facilitating faster labeling than previously possible using a focusedenergy emission source, such as an optical writing laser. As suggestedby the name, each of the thermally conductive pads (104) includes athermally conductive material. The thermally conductive material mayinclude, for example, carbon or other thermal conductors. Accordingly, afocused energy source may direct energy to any portion of an individualthermally conductive pad (104), and the thermally conductive pad (104)will absorbs the energy and substantially evenly distributes theabsorbed energy across the pad.

As the energy is absorbed and distributed across the thermallyconductive pad (104), the temperature of the pad increases. When theconductive pad (104) increases in temperature, the pad (104) transfersheat to portions of the thermochromic layer (110) adjacent to the pad(104). The heat transferred to the thermochromic layer (110) results inan optical density change for that portion of the thermochromic layer(110) that is heated. By selectively applying focused energy to thethermally conductive pads (104), a label of printed patterns and/orgraphical designs may be quickly added to the optical disc (100) in thethermochromic layer (110).

Instead of selectively writing a label to the optical disc (100) with a2.2 μm pixel size, the use of the thermally conductive pads (104)facilitates writing labels with a pixel size of 5–50 μm or greater,corresponding to the size of the thermally conductive pads (104). Thisdecreases the labeling write time by about 2–20 times or more. Inaddition to the example of an optical disc, the thermally conductivepads (104) may be combined with a thermochromic layer (110) and added toany other object to facilitate labeling of that object.

In addition to enabling faster label creation, the introduction of thethermally conductive pads (104) may add to the accuracy of the labels. Atypical 2.2 μm pixel created by writing to conventional optical discstends to be misshaped (tear-shaped or elliptical) because of therotation of the optical disc during writing. The use of specially shapedthermally conductive pads (104) ensures a desired pixel size and shape.And, although the thermally conductive pads (104) shown are all the samesize, this is not necessarily so. The size and shapes of the thermallyconductive pads (104) of an object may be uniform as shown, or may vary.Further, use of the relatively large thermally conductive pads (104)increases tolerance for positional errors of the focused energy emissionsource. Energy may be directed to any portion of the conductive pad(104), and the pad (104) will still substantially evenly distribute theenergy and uniformly heat the thermochromic layer (110).

The optical disc (100) (or other object) with the thermally conductivepads (104) may be made according to any of a number of methods.Particular methods of manufacture are discussed below, however, themethods discussed below are exemplary in nature and not limiting.Turning to FIGS. 4A–D, a series of side view images of the optical disc(100) is shown in various stages of disc manufacture. According to oneembodiment, the manufacture of the optical disc (100) includes indentingthe insulating layer (106). As mentioned above, the insulating layer(106) may be a polymer or other deformable material. A pattern,preferably a uniform pattern, is stamped into the insulating layer (106)to form a plurality of indentations (400). The shape of the indentations(from a top view) corresponds with the hexagonal, curved, circular,elliptical, or other shapes discussed above and/or shown in FIGS. 1–3 asbeing possible shapes for the thermally conductive pads. The pattern maybe stamped with a rigid die or other tool. Alternatively, the pattern ofindentations (400) may be microembossed into the insulating layer (106)or screen-printed onto the insulating layer (106). Other methods offorming the indentations (400) may also be used.

After indenting a pattern onto the insulating layer (106), a thermallyconductive material is deposited onto the insulating layer (106) and/orinto the indentations (400). For example, a thermally conductivematerial such as carbon in a solvent may be fluidly layered across theinsulating layer (106). One example of a carbon/solvent mixture is inkcommonly used in inkjet printers. Following application of a liquidconductive layer, the solvent is allowed to evaporate, leaving the solidcarbon or other thermally conductive material in the indentations (400).Alternatively, the thermally conductive material may be inserteddirectly into the individual indentations (400), and there may be noneed for an evaporation time allowance. The thermally conductivematerial disposed in the indentations defines the thermally conductivepads (104) shown in FIG. 4B.

Following the formation of the thermally conductive pads (104), thethermochromic layer (110) is disposed over the thermally conductive pads(104) and the insulating layer (106) as shown in FIG. 4C. Thethermochromic layer (110) may include leuco dye or other materials knownto change color with the application of heat. Preferably, thethermochromic layer (110) is initially transparent to the wavelength oflight generated by an energy emitter, for example, a writing laser. Thematerial of the thermally conductive pads (104), on the other hand, ishighly absorptive of the wavelength of energy emitted.

An optically transparent layer (112) may be disposed over thethermochromic layer (10) as shown in FIG. 4D, although this is notnecessarily so. According to some embodiments, there is no opticallytransparent layer (112) in addition to the thermochromic layer (110).The transparent layer (112) may be, for example, polycarbonate or someother protective material. The transparent layer (112) may bespin-coated onto the thermochromic layer (110) and protects thethermochromic layer (110) and/or the conductive pads (104) fromscratches or other damage.

It will be understood that opposite of the label side (102, FIG. 1) ofthe optical disc (100, FIG. 1) will normally be a data side (114, FIG.1). The data side (104, FIG. 1) may be fabricated according toconventional methods that are well known to those of skill in the arthaving the benefit of this disclosure. The data side (104, FIG. 1)therefore includes all of the layers typical of writable or rewritableoptical discs in various formats. However, according to someembodiments, there may be two label sides (102, FIG. 1) and no data side(104, FIG. 1). According to embodiments with two label sides (102, FIG.1), only printed patterns and graphical designs may be created, and nodigital data may be recorded.

In an alternative construction, a specialty film could be made toinclude the thermally conductive pads and an insulator. The specialtyfilm could then be applied to an object such as an optical disc, but itmay also be added to any other object to facilitate labeling.

According to some aspects of the construction of an optical disc, alabel side may also include some permanent information that is human ormachine readable. Such permanent information may include, but is notlimited to: the optical disc format, the color that will be viewablewhen the optical density of the thermochromic layer is changed, etc.

Turning now to a discussion of an actual labeling operation according tothe principles discussed herein, labeling of the optical disc (100,FIG. 1) or other objects may be accomplished with a number ofcommercially available products. For example, a computer with a CDRead/Write (RW) or DVD-RW drive may be used to label the optical disc(100, FIG. 1). However, other products capable of writing to opticaldiscs may also be used including, but not limited to, CD and DVDrecorders. For purposes of example and discussion, a computer system(500) that may be used in combination with the optical disc (100) togenerate a label thereon is shown in FIG. 5.

The computer system (500) includes a mount (502) and a motor (504) forholding and spinning the optical disc (100). The label side (102) of thedisc (100) is shown facing the mount (502) such that a label may bewritten to the disc (100). It will be understood, of course, that datamay also be written to the data side (114) of the optical disc (100) ifthe disc is turned over.

Positioned to face a portion of the label side (102) of the optical disc(100) is a track (506) providing for movement of a sled (508) radiallywith respect to the optical disc (100). Movement of the sled (508) isactuated by a solenoid (509) or other device. A focused energy emittingdevice or devices, which in the present embodiment includes a first,second and third laser (510, 512, 514, respectively), is disposed on thesled (508). The first laser (510) is a writing laser with enough powerto quickly heat the thermally conductive pads (104, FIG. 1) of theoptical disc (100). The second laser (512) is an erasing laser that maybe used, for example, to erase CDRW discs. The third laser (514) is aread laser and is less powerful than the first and second lasers (510and 512) and may be used to emit a beam that is reflected and read by adetector (516). The detector (516) is also positioned on the sled (508).The third laser (514) is used when reading data from the data side (114)of the optical disc (or, in some cases, some data from the label side(102). Signals received by the detector may be conditioned by a signalconditioner (515) when the system (500) is in a reading mode.

However, the system (500) is in a writing mode as shown in FIG. 5 and asthe optical disc (100) spins, a label can be written on the label side(102) by applying the first laser beam (540) from the first laser (510)at selective locations. The system is controlled by a processor (520).The processor (520) controls the firing of the lasers (510, 512, 514),the rotation of the motor (504), and the position of the sled (508). Thefirst laser (510) can aim an energy beam (540) very precisely to hit oneor more of the thermally conductive pads (104, FIG. 1).

When the energy beam (540) strikes one of the thermally conductive pads(104, FIG. 1), the conductive material evenly distributes the energyacross the pad (104, FIG. 1) and increases in temperature. The resultingincrease in temperature heats a portion of the thermochromic layer (110)corresponding to the shape and size of the thermally conductive pad(104, FIG. 1) that the thermochromic layer (110) is adjacent to. With anincrease in temperature, that portion of thermochromic layer (110)adjacent to the thermally conductive pads (104, FIG. 1) changes opticaldensity and becomes visible, colored or non-transparent. It should benoted that heat transfer from the thermally conductive pad (104, FIG. 1)to the thermochromic layer (110) will continue even after the energybeam (540) has moved to another pad (104). Therefore, the label writingprocess can proceed quickly as the laser (510) is aimed to strikedifferent conductive pads (104, FIG. 1). The laser need only be appliedlong enough to sufficiently heat the conductive pad (104, FIG. 1) anddoes not have to be applied until the thermochromic layer (110) haschanged optical properties.

The first laser (510) applies the energy beam (540) to all locationsprogrammed in the processor (520) to create a label, e.g., printedpattern and/or graphical display. For example, the first laser (510) mayapply energy to selective thermally conductive pads (104) to create aprinted pattern (600) or graphical design (602) as shown in FIG. 6. Aninset (604) shows that individual pixels (606) have been selectivelycolored by the application of energy to associated conductive pads(104).

The preceding description has been presented only to illustrate anddescribe embodiments of invention. It is not intended to be exhaustiveor to limit the invention to any precise form disclosed. Manymodifications and variations are possible in light of the aboveteaching. The principles described herein, including using thermallyconductive pads under a thermochromic material, may be adapted to anyobject. It is intended that the scope of the invention be defined by thefollowing claims.

1. A method of visually labeling an object comprising selectivelyapplying focused energy to thermally conductive pads on said object toheat said thermally conductive pads on said object, wherein said heatcreates to a permanent, visible label on said object, said labelcomprising a printed pattern or a graphical design, wherein saidconductive pads are disposed adjacent to a thermochromic layer, andwherein an optical property of corresponding portions of saidthermochromic layer changes in response to said heat of said thermallyconductive pads to form said permanent, visible label.
 2. The method ofclaim 1, wherein said thermally conductive pads correspond to pixels insaid label.
 3. The method of claim 1, further comprising changing anoptical density of said portions of said thermochromic layer with saidselective heating to form said visible label.
 4. The method of claim 1,wherein said conductive pads are between five and fifty μm across. 5.The method of claim 1, wherein said conductive pads have a hexagonalshape.
 6. The method of claim 1, wherein said conductive pads have anelliptical shape.
 7. The method of claim 1, wherein said conductive padshave a circular shape.
 8. The method of claim 1, wherein said label isprinted with a resolution of 5 μm or greater.
 9. The method of claim 1,wherein said printed pattern comprises legible text.
 10. A method ofusing an optical disc comprising applying focused energy in apredetermined pattern to a plurality of thermally conductive pads formedon said optical disc to heat selected thermally conductive pads, whichheat creates a permanent, visible, human-readable label on a non-dataside of said disc.
 11. The method of claim 10, further comprisingheating portions of a thermochromic layer with corresponding thermallyconductive pads that are heated by said focused energy, wherein saidheating portions of said thermochromic layer causes the heated portionsto change optical properties thereby forming said visible label.
 12. Themethod of claim 10, wherein each of said plurality of thermallyconductive pads represents a pixel of said visible label and has a pixelsize of approximately five to fifty μm.
 13. The method of claim 10,wherein each of said thermally conductive pads has a hexagonal,circular, or elliptical shape.
 14. The method of claim 10, wherein eachof said thermally conductive pads comprises a thermally conductivematerial disposed in an indent formed in said optical disc.
 15. A methodof labeling an optical disc comprising selectively applying laser lightto thermally conductive pads formed in said optical disc to create apermanent, visible label on a non-data side of said disc, said labelbeing indicative to a human user of data stored on an apposite, dataside of said optical disc, wherein said thermally conductive pads aredisposed adjacent to a thermochromic layer.
 16. The method of claim 15,further comprising heating portions of said thermochromic layercorresponding to selected thermally conductive pads.
 17. The method ofclaim 16, further comprising changing an optical density of portions ofsaid thermochromic layer adjacent to selected conductive pads to formsaid visible label.
 18. The method of claim 15, wherein said conductivepads have a hexagonal, elliptical, or circular shape.
 19. A method oflabeling an object comprising selectively applying focused energy to aplurality of thermally conductive pads on said object so as to heatselected thermally conductive pads with said focused energy; whereinsaid conductive pads are disposed adjacent to a tbermochromic layer andheating of said selected thermally conductive pads is sufficient tocause corresponding portions of said thermochromic layer to permanentlychange optical properties so as to form a visible label in saidthermochromic layer on said object.
 20. The method of claim 19, whereinsaid corresponding portions of said thermochromic layer change theiroptical density in response to said heating so as to form said label.21. The method of claim 19, wherein said conductive pads are betweenfive and fifty μm across.
 22. The method of claim 19, wherein saidconductive pads have a hexagonal shape.
 23. The method of claim 19,wherein said conductive pads have an elliptical shape.
 24. The method ofclaim 19, wherein said conductive pads have a circular shape.
 25. Themethod of claim 19, wherein selectively applying focused energycomprises applying a laser to selectively heat said thermally conductivepads.
 26. The method of claim 25, wherein said object comprises anoptical disc and said method further comprises applying said laser withan optical read/write disc drive.